The present invention relates generally to on-line (O/L) database reorganization (ODBR) in O/L transaction processing (OLTP) systems, and more particularly to collision detection and data corruption protection during an ODBR.
In certain computing environments, multiple processors communicate with multiple control units to provide access to storage devices. In many cases, two or more processors access data located in a single, shared database. Locking mechanisms and application agreed upon protocols have been implemented in these environments to serialize accesses to the database in order to protect data integrity. Locking mechanisms are of particular importance when a portion of the data in the shared database is scheduled to be updated by an application executing on one of the processors. In this case, the application is typically given an “exclusive lock” that prevents other applications and/or processors from accessing the data while it is being updated.
Database reorganizations are performed to reconfigure and relocate data records within a database. Database reorganizations may be utilized to improve the performance of database accesses. For example, a database reorganization may be used to build new indexes or to store existing indexes in a different format. Additionally, database reorganizations may be used to store data that is frequently accessed as a unit in a manner that provides high performance access for particular applications. Database reorganizations may also be performed when additional storage devices are made available to store data located in the database (e.g., due to system growth). During database reorganizations, it is important that the contents of the data records being reconfigured and/or relocated are not corrupted.